1. Field of the Invention
The present invention relates to a method of data transfer, and, more particularly, to an apparatus and a method of reading, encrypting, and transferring data read from a recording medium to an external device.
2. Description of the Related Art
Providing digital storage media, such as digital video disks (DVD), with copy protection mechanisms for protecting copyrighted data has become increasingly important It is desirable that a signal processor performing copy protection functions be implemented using a single chip processor. The signal processor must perform quantitative arithmetic processing, such as encryption, on the data read from the storage medium. The processed data is then transferred to an external unit or device, such as a personal computer. It would be advantageous to increase the speed of processing and transferring the data read from the recording medium to the personal computer.
FIG. 1 is a block diagram of a conventional DVD unit 50. Specifically, the DVD unit 50 for reading an optical disk 51 serving as a recording medium comprises: a DVD controller 53 which functions as a signal processor, a memory (DRAM) 54 which provides a temporary storage space for data read from the optical disk 51, and a micro processing unit (MPU) 55 which controls the signal processing operation of the DVD controller 53. The DVD controller 53 reads data recorded on the optical disk 51 and applies quantitative arithmetic processing or encryption processing on the data before it is transferred to an external unit such as a personal computer 52.
Specifically, the DVD controller 53 comprises an error correction circuit 58, an encryption circuit 56 for encrypting the data read from the optical disk 51 and stored in the DRAM 54, and an external interface (I/F) circuit 57 for enabling data communication with the personal computer 52. The encryption circuit 56 comprises a cipher generator circuit 56a and an encryption arithmetic circuit 56b, which uses cipher data generated by the cipher generator circuit 56a to apply an arithmetic operation on the data read from the DRAM 54 and stores the processed data back in the DRAM 54 as encrypted data.
The DVD controller 53 also transfers the encrypted data stored in the DRAM 54 to the personal computer 52 through the interface circuit 57. The personal computer 52 then decodes the encrypted and transferred data to recover the data read from the optical disk 51.
As a result of the ever increasing processing speeds of personal computers, there is a demand imposed on the DVD controller 53 to decrease the processing time required to read and encrypt the data read from the optical disk 51.
However, the processing operation for the encryption requires:
(1) transferring the data stored in the DRAM 54 to the encryption circuit; PA1 (2) transferring the encrypted data from the encryption circuit to the DRAM 54; and PA1 (3) transferring the encrypted data stored in the DRAM 54 to the interface circuit 57.
Thus, the DVD controller 53 must perform three accesses to the DRAM 54, which stands in the way of achieving a higher rate of data throughput.
It is an object of the present invention to provide a data transfer method and a signal processor which enable a high rate of data transfer.